1. a matter dealt with in a text, discourse, or conversation; a subject: "sleep deprivation became a frequent topic of conversation"
▪ that part of a sentence about which something is said, typically the first major constituent.
Word Originlate 15th century (originally denoting a set or book of general rules or ideas): from Latin topica, from Greek ta topika, literally ‘matters concerning commonplaces’ (the title of a treatise by Aristotle), from topos ‘a place’.